Master Lock 6121D 2-1/8″ (54mm) Wide ProSeries Weather Tough Laminated Steel Rekeyable Pin Tumbler Padlock

The Master Lock 6121D ProSeries Weather Tough Padlock is engineered for the toughest outdoor conditions and high-security applications. Built with a 2-1/8 inch (54mm) laminated steel body and protected by a durable Weather Tough® thermoplastic cover, this padlock resists corrosion, moisture, dirt, and freezing conditions. The 1-1/8 inch (29mm) tall hardened boron alloy shackle is 5/16 inch (8mm) in diameter, offering superior cut resistance for high-risk sites such as trailers, truck doors, security gates, and fences.

Its internal components are designed for extreme reliability, featuring a high-security rekeyable 5-pin cylinder with spool pins that make picking virtually impossible. The dual ball locking mechanism adds extra strength against prying and pulling, making this lock a powerful choice for commercial fleets, transport companies, and remote outdoor storage locations.

Master Lock 2-1/8″ (54mm)  Rekeyable Weather Tough Laminated Steel Padlock At a Glance

• Weather Tough® thermoplastic cover: Shields the lock from water, ice, grime, and extreme temperatures
• 2-1/8 in laminated steel body: Withstands physical abuse and impact in harsh environments
• Hardened boron alloy shackle: Delivers maximum resistance to bolt cutters and sawing
• High-security 5-pin cylinder: Rekeyable with spool pins that make lockpicking extremely difficult
• Dual ball bearing locking mechanism: Offers strong defense against pulling and prying attacks
• Commercial-grade design: Engineered for use in industrial, fleet, and severe-duty applications
• Carded retail packaging: Ideal for showroom display and resale

Markets

• Transportation & Towing Protects cargo trailers, moving trucks, and fleet vehicles with a high-security, weatherproof solution.
• Truck & Van Fleets Locks rear doors, tool compartments, and side access points with resistance to cutting and pulling.
• Construction & Job Sites Secures gates, equipment sheds, and perimeter fences under severe environmental and physical stress.
• Municipal Services Protects public works trailers and gated utility access areas from unauthorized access and tampering.
• Marine & Coastal Operations Resists corrosion and buildup from salt air and moisture on docks, trailers, and boat storage areas.
• Outdoor Equipment Rentals Used to safeguard mobile storage, temporary fencing, or equipment containers left outdoors.
• Agriculture & Farming Ideal for securing machinery sheds, fuel tanks, and gated property access in rural environments.

The Master Lock 6121D ProSeries Weather Tough Padlock Provides Proven Security for Trailers, Truck Doors, and Harsh Weather Conditions. When outdoor gear, vehicle fleets, or jobsite equipment need serious protection, the 6121D lock offers durable, rekeyable security in all seasons. It’s ideal for companies managing trailers or cargo vans across changing weather, as well as for fencing and perimeter security in remote locations. Whether you’re dealing with freezing rain, dusty backroads, or damp marine air, this lock is designed to last and built to secure—day in and day out.

Master Lock 6121D 2-1/8in (54mm) Wide ProSeries Weather Tough Laminated Steel Rekeyable Pin Tumbler Padlock Features

• Ideal for harsh outdoor conditions – exclusive Pro Series Weather Tough cover protects lock from water, ice, dirt and grime
• ProSeries Padlocks are designed for Commercial/Industrial applications
• 2-1/8in (54mm) heavy steel body withstands physical attack
• 1-1/8in (29mm) tall, 5/16in (8mm) diameter hardened boron alloy shackle for maximum cut resistance
• Dual ball locking mechanism resists pulling and prying
• High security, rekeyable 5-pin cylinder with spool pins is virtually impossible to pick
• Carded packaging for showroom display
• Best Used For: Severe Use – Security Gates & Fences, Trailers, Trucks, & Towing, Trailers, Vans & Moving Trucks, Truck Doors

Master Lock 6121D 2-1/8″ (54mm) Wide ProSeries Weather Tough Laminated Steel Rekeyable Pin Tumbler Padlock Specifications

• Product Number: 6121D
• Body Width: 2-1/8 in (54 mm)
• Shackle Length: 1-1/8 in (29 mm)
• Shackle Width: 7/8 in (22 mm)
• Shackle Diameter: 5/16 in (8 mm)
• Color: Black
• Material: Laminated steel body with hardened boron alloy shackle
• Lock Type: Rekeyable, keyed different
• Packaging: Commercial carded
• Shelf Pack Quantity: 4
• Master Carton Quantity: 24
• Warranty: Master Lock Limited Lifetime Warranty

Master Lock 6121D 2-1/8in (54mm) Wide ProSeries Weather Tough Laminated Steel Rekeyable Pin Tumbler Padlock Manufacturer Warranty

• Master Lock’s Limited Lifetime Warranty

Why Professionals Choose the Master Lock 2-1/8″ (54mm) Wide ProSeries Weather Tough Laminated Padlock

In the field, this padlock is often referred to as a “trailer lock” or “fleet lock” due to its proven strength in securing transport vehicles and cargo. Professionals rely on it when equipment needs to stay put, no matter the weather or location. With its rekeyable pin tumbler core, resilient laminated body, and corrosion-resistant shell, the 6121D is a go-to for severe-use padlock applications. It works as hard as the people who depend on it—holding strong against both the elements and intruders.